In the manufacture (erection and taping of flaps to produce a carton or case from a knocked down blank) the knocked down carton or case is first squared and then the bottom flaps folded into closed position. The squaring operation generally withdraws a single knocked down case blank from a magazine of such blanks held in face to face position, opens the blank from the knocked down condition into a squared condition wherein adjacent side walls of the case are generally mutually perpendicular and positions the squared blank into a bottom flap folding station. In the bottom flap folding station the minor flaps (generally the shorter flaps) one connected to each of the leading and trailing side panels of the case (oriented in the direction of travel of the case from the erecting station) are folded relative to their respective side panels and then the major flaps one connected to each of the remaining side wall (walls parallel to the direction of travel) are folded into underlining relation (outwardly exposed relation) to the minor flaps. The so erected case is then moved into a bottom closure station which may be a taping station where a tape or adhesive is applied along the bottom major flaps extending in the direction of travel of the case through the taping station to secure the major flaps in folded closed position and thereby the case in squared condition with the adjacent side panels mutually perpendicular. In this condition the top closing flaps are generally in open position so that the case may be filled and then the top flaps are closed and secured in closed position for example by taping or adhesive similar to the bottom taping operation to complete the erecting filling and closing cycle and the filed box is ready for shipment.
U.S. Pat. No. 4,553,954 issued Nov. 10, 1985 to Sewell et al. describes the erector to which the present invention is a significant improvement and the disclosure of this patent is incorporated herein by reference. This patent teaches the use of relatively pivoting jaws a fixed jaw oriented perpendicular to the direction of travel of a case through the erector i.e. from a bottom erector station and a moveable jaw that pivots on a pivotal axis between a pick-up or gripping position with the moveable jaw substantially parallel to and spaced from the fixed jaw to a position perpendicular to the fixed jaw. These erectors normally are designed to erect case blanks having significantly different thicknesses so the erector is normally made so that the spacing between the moveable and fixed jaws in the parallel position is adjustable to accommodate knocked down case blanks of different thicknesses. This is accomplished in the prior art by moving the fixed jaw.
The jaws grip the top flaps extending from a pair of adjacent side panels of a case and open (square) the case by pivoting the moveable jaw on the pivotal axis. These jaws in their mutually perpendicular position (open or squaring position) then move the so opened (squared) case down into the bottom erecting station wherein bottom flaps are folded as above described.
In the prior art system a single substantially circular stabilizer bar is removably mounted on the fixed jaw and extends in an arc centered on the pivot axis or hinge point between the jaws and passes through suitable opening in the moveable jaw (to permit the relative movement of the moveable jaw between parallel (pick-up) and open (squaring) position). The stabilizer bar is positioned with its bottom edge in position to contact with top edges of the other major and minor top flaps adjacent to the free corner (corner remote from the pivotal axis) of the case to keep the case in proper orientation i.e. stop the free corner of the case from moving upward as the case is moved into the bottom forming station. The stabilizer bar must be moveably mounted to accommodate different sized cases i.e. cases having their free corner spaced from the pivotal axis by significantly different lengths and the above described thickness adjustment (change in the space between the fixed and moveable jaws in the parallel pick-up or gripping position) to position the stabilizer bar in a position whereby it will pass through holes in the moveable jaw positioned between adjacent grippers.
In the prior art machine wherein the stabilizer bar position required adjustment when significantly different sized boxes or cases were to be erected the spacing between the jaws in the parallel pick up position which also had to be changed when knocked down blanks for cases of significantly different thickness were to be erected, was adjusted by physically moving the fixed jaw. Movement of the fixed jaw requires unbolting the fixed jaw, moving it and bolting it back in position which also required in many cases that the separator bar that moves the lead blank down from the magazine (see U.S. Pat. No. 4,553,954) required adjustment to be properly positioned relative to the fixed jaw in its new position. These procedures required a significant amount of time and skill to ready the machine to process blanks of the new (different) thickness.